Author(s): Angelo Verzoni. Published on August 1, 2017.

London Calling

Experts say the problems that led to the deadly Grenfell Tower fire in Great Britain may exist in hundreds of buildings around the world. That’s why NFPA is developing an array of resources to address issues related to combustible exterior wall assemblies.


In 1666, London burned. Flames swept across the city like a tsunami, displacing 70,000 of the city’s 80,000 residents. Astonishingly, few people died; there were only six verified deaths.

Related Content

Read the Fire Protection Research Foundation’s 2014 report, “Fire Hazards of Exterior Wall Assemblies Containing Combustible Components.”

Read BRE Global’s report on its fire testing of exterior wall assemblies in the U.K.


Fast-forward to 2017, when a much smaller London fire recently proved far more deadly. At least 80 people died in the June 14 Grenfell Tower blaze in West London, making it the deadliest fire in modern British history. After 351 years of fire and life safety advancements, how could so many more people die in that fire than in the Great Fire of London? The answer lies in part in modern construction methods.

As part of a 2015-16 renovation project on the 24-story Grenfell Tower apartment building, built in 1974, exterior walls on the structure had been retrofitted with what has been widely reported as a combination of aluminum composite panels containing polyethylene plastic and foam insulation board, both considered to be combustible. When a refrigerator in a fourth-floor apartment sparked a fire, the blaze found its way to the outside of the building, igniting the combustible wall assembly materials that quickly funneled flames skyward. Fire not only raced up and around the sides of the building, but it also spread from the outside in, gutting the entire structure. According to one Grenfell resident who was interviewed by The New York Times, the conflagration “burned like a fire that you pour petrol on.” Additional fire safety issues were present, too. There were no fire sprinklers (which aren’t required by United Kingdom regulations) or functioning fire alarms, there was only one stairwell, and emergency procedures for the tenants included a “stay put” order unless fire was inside their apartment unit.

In the weeks following Grenfell, investigators flocked to similar buildings throughout Great Britain. Samples of exterior wall assemblies, including various combinations of metal composite material (MCM) panels and insulation, were removed and subjected to what have been reported as “government combustibility tests.” As a result of the tests, hundreds of buildings were declared unsafe, and thousands of people were ordered to evacuate their homes. On July 28, the British government announced there would be an independent review to examine “the regulatory system around the design, construction and on-going management of buildings in relation to fire safety; related compliance and enforcement issues; and international regulation and experience in this area.”

The problem of combustible exterior wall assemblies isn’t new—fires involving these types of assemblies have occurred all over the world, including the United States—but Britain’s recent experience illustrates a new global urgency behind the issue. Government officials, safety advocates, and the media are raising questions as to the prevalence of combustible exterior wall assemblies on buildings worldwide, and what can be done to prevent potentially catastrophic fires from occurring.

Members of the emergency services work on the middle floors of the charred remnains of the Grenfell Tower block in Kensington, west London

COMBUSTIBLE FAÇADE At least 80 people died in a fire that tore through Grenfell Tower, a high-rise apartment building in West London, on June 14. A combustible exterior wall assembly, including the insulation and cladding that sheathed the building, is believed to have contributed to the rapid spread of the blaze. Photograph: Getty Images

NFPA hopes to help answer those questions by making an assortment of resources available to stakeholders, including a new risk assessment tool designed for authorities having jurisdiction (AHJs). Those tools can’t arrive soon enough, experts say. “In many of our larger cities or jurisdictions, you’re dealing in some cases with quite a few of these buildings [that could be at risk],” said J.C. Harrington, staff vice president at FM Global. “Maybe in the hundreds worldwide.”

Quantifying the problem

Exterior wall assemblies can have many different configurations, but a common arrangement is for plastic foam insulation to be attached to the structure, separated by a narrow gap from an outer layer comprised of thin metal panels sandwiching a plastic core; this was the configuration believed to be on Grenfell. (Media accounts commonly refer to these combustible assemblies as “flammable exterior cladding,” a term that is inconsistent with most code language and only points to one component of these assemblies.) Despite the known concerns, the assemblies are popular because they contribute to energy efficiency for the building, help prevent rain and moisture penetration, and give buildings a clean, modern appearance.

To address those concerns, NFPA is developing a tool that allows AHJs—specifically, enforcers—to determine which buildings in their jurisdictions are at the highest risk for fires involving combustible exterior wall assemblies. The tool, which NFPA hopes to make available by the end of the year, will factor in variables such as building materials, height and configuration, and whether fire protection systems like fire sprinklers are present. The inventory will also shed light on which exterior wall systems containing combustible material have been deemed safe and by which fire test procedure.

International engineering firms Arup and Jensen Hughes are also involved in the project, as is an international panel of technical experts facilitated by the Fire Protection Research Foundation (FPRF). Panelists “were chosen for their technical expertise, and we also tried to be very global with who we put on,” said Amanda Kimball, a research director at the FPRF. “We have perspectives from Asia, the Middle East, Europe, Australia, and the United States.”

Casey Grant, who heads the FPRF, explained that the tool won’t be designed to tell AHJs how to fix the problems, but rather to let them know if problems exist, and the severity of the problems. “It’s not as simple as saying, ‘this building has a combustible exterior wall assembly and this one doesn’t,’” Grant said. “This is all about developing for enforcers a risk assessment tool to prioritize their inventory.”

While its primary audience is AHJs, the tool will be available to anyone who wants to use it. The hope is for the tool to serve as a springboard for fire and life safety experts as they become more involved with the issue, since a large part of the problem is an uncertainty that exists worldwide surrounding the prevalence of at-risk combustible exterior wall assemblies. “There’s a need to look at the attributes of these different systems and come up with an organized approach, on a risk basis, for determining how an AHJ or a municipality might evaluate the existing building stock,” said Harrington, a member of the project’s technical panel

In the U.K., at least, the picture is becoming clearer, thanks to the activity prompted by the Grenfell fire. According to a recent ABC News feature, at least 600 buildings in Britain are thought to have an exterior wall assembly similar to the one Grenfell had. Elsewhere, such as Dubai, in the United Arab Emirates, the problem is also apparent. When the 63-story Address hotel in downtown Dubai caught fire on New Year’s Eve 2015, onlookers captured stunning videos of the flames shooting up the tower’s façade in a matter of minutes. Five similar fires involving combustible exterior wall assemblies have occurred in Dubai since 2012. Two of those fires involved the same building—a 79-story residential tower named “the Torch”—which suffered extensive damage after flames shot up its sides in 2015 and again in August of this year.

A 2014 FPRF report on combustible exterior wall assemblies illustrated how the problem extends to all corners of the globe. The report identified fires involving combustible exterior wall assemblies dating back to 1990 in Australia, Canada, China, France, Germany, Hungary, Japan, Russia, South Korea, the United Arab Emirates, the U.K., and the U.S. “It’s certainly not a problem unique to the U.K.,” Harrington said.

An imperfect model?

On June 24, The New York Times published an article that posed the question, why did Grenfell burn? It’s a simple question whose answer lies in decades of failed policy changes.

The newspaper revealed that as far back as 1999, firefighters and engineers warned Parliament that British building codes weren’t sufficiently written to address the risk of vertical fire spread on buildings with combustible exterior wall assemblies. Industry proponents pushed back against the warnings, though, and no code changes were made. Consequently, high-rise buildings with combustible exterior wall assemblies are thought to be widespread in Britain, as evidenced by the scramble to now inspect buildings similar to Grenfell.

With stricter building codes than the U.K., the United States is often thought to be a model for properly vetting exterior wall assemblies. That doesn’t mean fires involving exterior wall assemblies don’t occur in the U.S. In fact, of 32 exterior wall fires in high-rises worldwide that were reported by various news sources from 2014 to June 28, 2017, nearly half occurred in the U.S. But few were severe, mostly occurring on assemblies that were added for aesthetics and contained to portions of the building.

Combustible Components Graphic

Illustration: Reuters

On the surface, the absence of severe exterior wall assembly fires in the U.S. seems like a testament to the successes of North American codes and standards like NFPA 285, Fire Test Method for Evaluation of Fire Propagation Characteristics of Exterior Non-Load-Bearing Wall Assemblies Containing Combustible Components. NFPA 285 outlines a rigorous full-scale testing procedure for exterior wall assemblies, and in practice prohibits assemblies like the one on Grenfell from being wrapped around high-rise buildings.

Dig deeper, however, and questions arise as to whether NFPA 285 is being followed correctly and if the U.S. could in fact experience a fire like Grenfell.

“My understanding is we have this issue all over Europe, we have this issue in the U.S., and in Asia and the Middle East,” said Didier Schutz, an engineer with SCOR, a global reinsurance company, who presented a session on combustible exterior wall assemblies at the NFPA annual conference in 2016. “It’s a worldwide problem.”

A month after the Grenfell blaze, local news sources in Baltimore reported that one of the city’s high-rises, a 32-story Marriott hotel, might be covered with the same aluminum composite panels that sheathed Grenfell—a product called Reynobond, manufactured by the Pittsburgh-based company Arconic. The Baltimore Marriott is a microcosm for what fire safety experts fear might be a larger problem in the U.S.: the possibility that builders and facility managers have in recent years circumvented or otherwise ignored NFPA 285, either by mistake or intentionally to cut costs.

Fire damaged apartments sit on the upper floors of the Address Downtown Dubai hotel   Picture outside of the Baltimore Marriott hotel.

A WORLDWIDE PROBLEM Safety experts fear combustible exterior wall assemblies like the one that burned in London in June are common on buildings across the globe. Above left, the Address hotel in Dubai following a fire on New Year’s Eve in 2015, where a combustible exterior wall assembly contributed to the rapid spread of flames. News sources in Baltimore have reported that the Marriott hotel on the city’s waterfront (right) may have the same cladding as that used on the Grenfell Tower in London. Photograph: Left, Getty Images. Right, Matt Pollack

One possible explanation for mistakenly overlooking NFPA 285 is that there is no set standard for the terminology used for these assemblies, leading to the possibility of confusion among architects, engineers, builders, and facility managers as to whether the standard is needed when they’re faced with a sea of overlapping and inconsistent terms. Concepts like cladding, curtain walls, exterior wall assemblies, insulated metal panels, metal composite material, rain screens, and more can refer to the same components and assemblies, or to different ones, or to various combinations of components.

Further complications arise because some exterior wall assemblies were installed before NFPA 285 was available and referenced by the governing building codes; the first edition of NFPA 285 came out in 1998. Additionally, when assemblies have been tested to NFPA 285, any modifications to them that deviate from the tested configuration could degrade fire behavior. “Building owners may have assemblies they think comply with the right standards, like NFPA 285, but that isn’t necessarily the case,” said Tracy Vecchiarelli, the NFPA staff liaison for NFPA 285. “They don’t really know what they have.”

Issues can also stem from the way the International Building Code liberalized the use of these systems. Unlike NFPA 5000, Building Construction and Safety Code, the 2012 edition of the IBC allows for buildings of any height to avoid testing exterior wall assemblies to NFPA 285 if they meet certain criteria, such as having fire sprinklers, limiting the area of the building walls being covered, and providing additional fire separation distances. In the past, the IBC generally required NFPA 285 testing for exterior wall assemblies with combustible materials on buildings over 40 feet tall.

To help clear things up, Vecchiarelli recently headed a team of NFPA staff to create an interactive flow chart explaining when to use NFPA 285. The online tool was built primarily for architects and engineers, who can click through a series of questions that includes which building code they’re using, whether a building’s walls are load bearing, the building’s construction type, and more. It includes photos, videos, and definitions to guide users through the process easily. The flow chart, coupled with the risk assessment tool being developed by NFPA, is designed to raise awareness and knowledge of combustible exterior wall assemblies and NFPA 285 among AHJs, designers, builders, and facility managers.

Outside of the U.S., tests similar to NFPA 285 exist, such as BS 8414, a BRE Global standard used in the U.K. and parts of the Middle East and Asia, and FM Global’s Approval Standard 4880. Like NFPA 285, these are full-scale tests that apply fire to a constructed wall assembly to observe how its spreads. But in the U.K., for example, exceptions allow builders and facility managers to avoid a full-scale test it if the wall assembly components, when tested individually, pass small-scale combustibility tests. The process stands in contrast to NFPA 285, which says that exterior wall assemblies must be tested as a whole system in an environment that replicates real-world conditions as accurately as possible.

A report released in late July by BRE Global, an independent, U.K.-based products-testing organization, showed that an assembly containing the same aluminum composite material (ACM) panels and foam insulation board believed to have been on Grenfell and configured in a way that is “representative of the systems that are in common use on buildings” failed BS 8414. The polyethylene core of those ACM panels also rated the highest level of combustibility, category 3, when tested alone, the report states.

Worldwide problem

Photographs: 1, Matt Pollack; 2-4, Getty Images

Worldwide, the proliferation of combustible exterior wall assemblies has coincided with efforts to refurbish aging, unattractive high-rises, many built in the 1970s, as well as efforts to increase energy efficiency in both new and old buildings. While there are options to insulate buildings in a more fire-safe manner, such as using glass wool or rock wool instead of plastic, those materials are more expensive. Usually, twice as much material is required to achieve the same energy efficiency, Schutz said. “It’s not so easy to install glass wool or rock wool,” he said. “Plastic is easy.”

So what’s worth more, convenience or safety? Schutz fears that if builders and facility managers keep choosing the former, more people could die in fires involving combustible exterior wall assemblies. “It’s frightening,” he said. “We may face more and more of these types of fires.”

ANGLEO VERZONI is staff writer for NFPA Journal. Top Photograph: Getty Images